1. Field of the Invention
The invention relates to a process for isolating polyorganosiloxanes from an aqueous dispersion.
2. Description of the Related Art
Polyorganosiloxanes such as the polyorganosiloxane particle known from U.S. Pat. No. 5,854,369, the core-shell particles known from U.S. Pat. No. 5,049,636, and MQ resins are frequently used as solids. A problem encountered here is that the products are produced in aqueous solution in the form of dispersions and subsequently have to be isolated. This can be achieved, for example, by spraying drying or freeze drying of the dispersions. A disadvantage of this method is that after drying, the emulsifier used for producing the dispersion remains in the product, or has to be removed therefrom, for example by washing of the dried product.
As an alternative, the above-described compounds can be isolated from the aqueous dispersions as an organosol, as described in U.S. Pat. No. 5,049,636. A disadvantage of this process is the complicated solvent exchange in which water is replaced by solvents, which consumes a great deal of energy. Furthermore, the emulsifier remains in the product in this process.